PB1815: ADDITIONAL СYTOGENETIC ABNORMALITIES IN ADULT ACUTE MYELOID LEUKEMIA WITH T(8;21)(Q22;Q22)

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Topic: 3. Acute myeloid leukemia - Biology & Translational Research Background: A reciprocal translocation involving chromosomes 8 and 21: t(8;21)(q22;q22) is one of the most frequent genetic aberration in adult acute myeloid leukemia (AML) and found in 5-10% of patients. Additional chromosomal abnormalities are often found (60-70%) in association with t(8;21)(q22;q22). The most common are: loss of X or Y, del(9q), trisomy of 4, 8 or 21 and others. These genetic abnormalities are important factors in determining response to chemotherapy as well as outcome in AML. Aims: Aim of this study was to detect additional chromosomal abnormalities in adult AML patients with t(8;21)(q22;q22) and determine frequency of them. Methods: Cytogenetic investigations of bone marrow and/or peripheral blood cells from 135 adult patients with AML were performed. The methods of conventional cytogenetics (GTG) and fluorescence in situ hybridization (FISH) were used. Cytogenetic methods were performed using standard techniques and karyotypes were described according to the International System for Human Cytogenetic Nomenclature. Results: Cytogenetic investigations were performed in 135 patients with AML. Chromosomal aberrations of various kinds were found in 80 (59%) cases. Taking into consideration the identified cytogenetic abnormalities AML patients were classified by prognostic groups: the group of patients with adverse cytogenetic markers (3q21q26 rearrangements, t(9;22)(q34;q11), BCR/ABL1 gene, del(5q), -7, complex karyotype (≥3 abnormalities)), the intermediate-risk group without significant markers (rare or atypical abnormalities, normal karyotype) and the group of patients with favorable prognostic factors (t(15;17)(q22;q21), PML/RARа gene, t(8;21)(q22;q22), AML1/ETO gene, inv(16)(p13q22), CBFβ/MYH11 gene). Translocation t(8;21)(q22;q22) was found in 8 (6%) cases. Of them 3 patients (37%) had only t(8;21)(q22;q22), whereas other 5 (63%) – had additional cytogenetic abnormalities. Spectrum of additional chromosomal aberrations was as follows: loss of Y (3 cases), monosomy of 20 (1 case) and del(9q) as part of a complex karyotype (1 case). Presence of the additional/secondary chromosomal aberrations in leukemic cells with t(8;21)(q22;q22) is the sign of clonal evolution and disease progression. Summary/Conclusion: In our study t(8;21)(q22;q22) was found in 6% of AML patients. The additional chromosomal abnormalities associated with t(8;21)(q22;q22), namely loss of Y, monosomy 20 and del(9q), were found in 63% of cases. Presence of the additional/secondary chromosomal aberrations in leukemic cells with t(8;21)(q22;q22) is the sign of clonal evolution and disease progression. Keywords: Acute myeloid leukemia, Cytogenetic abnormalities

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